arangosh> db._create("users", { keyOptions: { allowUserKeys: false } }); [ArangoCollection 15445, "users" (type document, status loaded)] arangosh> db.users.save({ name: "user 1" }); { "_id" : "users/15449", "_key" : "15449", "_rev" : "_XG3zGO2--_" } arangosh> db.users.save({ name: "user 2", _key: "myuser" }); [ArangoError 1222: unexpected document key] arangosh> db.users.save({ name: "user 3" }); { "_id" : "users/15454", "_key" : "15454", "_rev" : "_XG3zGO2--C" }